For every item returned in a response, the items associated with it are also returned if the Collections response group is used in the request. Items in collections are related thematically. For example, all of the linens that go into a bedroom might be associated in a bedding collection. The Collections response group returns the ASINs and titles of the items in a collection.

For more information, see Displaying Collections.

If an item is part of a collection and that item is returned in a response, all of the other items in the collection are also returned if the request contains the Collections response group.